Dyscalculia is a neurodevelopmental disorder that affects to the capacity for calculation, interfering with the academic performance, the level of social inclusion, the access to the working world, and especially in the realization, both personal and professional of the people who suffer it. This learning disability is nearly as common as dyslexia, nevertheless, it is studied much less, and it is worse understood, and so many times it is diagnosed inconsistently. With regard to academic performance, efforts are being made to improve learning, both at the level of the emerging scientific field of educational neuroscience and from the point of view of education. However, to date, scientists have only been studying how to help children affected by dyscalculia to develop new brain strategies that aim to improve their learning without taking into account the way to evaluate these learning. Through the exploration of subjacent neurocognitive processes inherent to practice and educational theory, the main objective of this work is to analyse the possible difference in the brain function of affected individuals with dyscalculia in the performance of evaluation tests in order to find the best way to be evaluated, to intervene in the strengthening of arithmetic processing and to improve their performance and self-esteem. The methodology used to achieve the desired goal is to analyse the activity of the brain during computation and answering test questions by using evoked potentials and to check with the dyscalculic students as they reasoned during the performing tests comparing them with students who do not have this learning difficulty. After the analysis carried out, we concluded that to evaluate students with dyscalculia, the test type should be avoided and must use alternative evaluation methods such as the oral examination, while at the same time allowing certain actions that can help them. Due to the difficulty of learning about the people who suffer this difficulty, the probability of them responding poorly in this kind of evaluation, regardless of the knowledge of the subject it is very high, so the result of the test is not valid to assess your learning, which is the final objective of the test